Gram-positive microorganisms, such as members of the genus Bacillus, are useful for large-scale industrial fermentation due, in part, to their ability to secrete their fermentation products into culture media. Secreted proteins are exported across a cell membrane and a cell wall, and then are subsequently released into the external media. Secretion of polypeptides into periplasmic space or into the culture media is an important subject that needs to be carefully considered in industrial fermentations.
Secretion of heterologous polypeptides from microorganisms is a widely used technique in industry. Typically, cells can be transformed with a nucleic acid encoding a heterologous polypeptide of interest. These transformed cells can then express the heterologous polypeptide of interest and thus secrete it in large quantities. This technique can be used to produce a greater amount of polypeptide than that which would be produced naturally. These expressed polypeptides have a number of industrial applications, including therapeutic and agricultural uses, as well as use in foods, cosmetics, cleaning compositions, animal feed, etc. There is a need in the field to provide hosts capable of secreting heterologous polypeptides.